better example for feature2 being implemented and integrated into the codebase

canvas/Cargo.toml

@@ -16,7 +16,7 @@ crossterm = { workspace = true, optional = true }
 anyhow.workspace = true
 tokio = { workspace = true, optional = true }
 toml = { workspace = true }
-serde = { workspace = true }
+serde.workspace = true
 unicode-width.workspace = true
 thiserror = { workspace = true }
 

canvas/examples/validation_2.rs

@@ -0,0 +1,647 @@
+// examples/validation_2.rs
+//! Advanced TUI Example demonstrating complex pattern filtering edge cases
+//!
+//! This example showcases the full potential of the pattern validation system
+//! with creative real-world scenarios and edge cases.
+//!
+//! Run with: cargo run --example validation_advanced_patterns --features "validation,gui"
+
+// REQUIRE validation and gui features
+#[cfg(not(all(feature = "validation", feature = "gui")))]
+compile_error!(
+    "This example requires the 'validation' and 'gui' features. \
+     Run with: cargo run --example validation_advanced_patterns --features \"validation,gui\""
+);
+
+use std::io;
+use std::sync::Arc;
+use canvas::ValidationResult;
+use crossterm::{
+    event::{
+        self, DisableMouseCapture, EnableMouseCapture, Event, KeyCode, KeyModifiers,
+    },
+    execute,
+    terminal::{
+        disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen,
+    },
+};
+use ratatui::{
+    backend::{Backend, CrosstermBackend},
+    layout::{Constraint, Direction, Layout, Rect},
+    style::{Color, Style},
+    text::{Line, Span},
+    widgets::{Block, Borders, Paragraph, Wrap},
+    Frame, Terminal,
+};
+
+use canvas::{
+    canvas::{
+        gui::render_canvas_default,
+        modes::AppMode,
+    },
+    DataProvider, FormEditor,
+    ValidationConfig, ValidationConfigBuilder, PatternFilters, PositionFilter, PositionRange, CharacterFilter,
+};
+
+// Enhanced FormEditor wrapper (keeping the same structure as before)
+struct AdvancedPatternFormEditor<D: DataProvider> {
+    editor: FormEditor<D>,
+    debug_message: String,
+    command_buffer: String,
+    validation_enabled: bool,
+    field_switch_blocked: bool,
+    block_reason: Option<String>,
+}
+
+impl<D: DataProvider> AdvancedPatternFormEditor<D> {
+    fn new(data_provider: D) -> Self {
+        let mut editor = FormEditor::new(data_provider);
+        editor.set_validation_enabled(true);
+
+        Self {
+            editor,
+            debug_message: "🚀 Advanced Pattern Validation - Showcasing edge cases and complex patterns!".to_string(),
+            command_buffer: String::new(),
+            validation_enabled: true,
+            field_switch_blocked: false,
+            block_reason: None,
+        }
+    }
+
+    // ... (keeping all the same methods as before for brevity)
+    // [All the previous methods: clear_command_buffer, add_to_command_buffer, etc.]
+    
+    fn clear_command_buffer(&mut self) { self.command_buffer.clear(); }
+    fn add_to_command_buffer(&mut self, ch: char) { self.command_buffer.push(ch); }
+    fn get_command_buffer(&self) -> &str { &self.command_buffer }
+    fn has_pending_command(&self) -> bool { !self.command_buffer.is_empty() }
+    
+    fn toggle_validation(&mut self) {
+        self.validation_enabled = !self.validation_enabled;
+        self.editor.set_validation_enabled(self.validation_enabled);
+        if self.validation_enabled {
+            self.debug_message = "✅ Advanced Pattern Validation ENABLED".to_string();
+        } else {
+            self.debug_message = "❌ Advanced Pattern Validation DISABLED".to_string();
+        }
+    }
+
+    fn move_left(&mut self) { self.editor.move_left(); self.field_switch_blocked = false; self.block_reason = None; }
+    fn move_right(&mut self) { self.editor.move_right(); self.field_switch_blocked = false; self.block_reason = None; }
+    
+    fn move_up(&mut self) {
+        match self.editor.move_up() {
+            Ok(()) => { self.update_field_validation_status(); self.field_switch_blocked = false; self.block_reason = None; }
+            Err(e) => { self.field_switch_blocked = true; self.block_reason = Some(e.to_string()); self.debug_message = format!("🚫 Field switch blocked: {}", e); }
+        }
+    }
+    
+    fn move_down(&mut self) {
+        match self.editor.move_down() {
+            Ok(()) => { self.update_field_validation_status(); self.field_switch_blocked = false; self.block_reason = None; }
+            Err(e) => { self.field_switch_blocked = true; self.block_reason = Some(e.to_string()); self.debug_message = format!("🚫 Field switch blocked: {}", e); }
+        }
+    }
+
+    fn move_line_start(&mut self) { self.editor.move_line_start(); }
+    fn move_line_end(&mut self) { self.editor.move_line_end(); }
+    
+    fn enter_edit_mode(&mut self) {
+        self.editor.enter_edit_mode();
+        self.debug_message = "✏️  INSERT MODE - Testing advanced pattern validation".to_string();
+    }
+    
+    fn enter_append_mode(&mut self) {
+        self.editor.enter_append_mode();
+        self.debug_message = "✏️  INSERT (append) - Advanced patterns active".to_string();
+    }
+    
+    fn exit_edit_mode(&mut self) {
+        self.editor.exit_edit_mode();
+        self.debug_message = "🔒 NORMAL MODE".to_string();
+        self.update_field_validation_status();
+    }
+
+    fn insert_char(&mut self, ch: char) -> anyhow::Result<()> {
+        let result = self.editor.insert_char(ch);
+        if result.is_ok() {
+            if let Some(validation_result) = self.editor.current_field_validation() {
+                match validation_result {
+                    ValidationResult::Valid => { self.debug_message = "✅ Character accepted".to_string(); }
+                    ValidationResult::Warning { message } => { self.debug_message = format!("⚠️  Warning: {}", message); }
+                    ValidationResult::Error { message } => { self.debug_message = format!("❌ Pattern violation: {}", message); }
+                }
+            }
+        }
+        Ok(result?)
+    }
+
+    fn delete_backward(&mut self) -> anyhow::Result<()> {
+        let result = self.editor.delete_backward();
+        if result.is_ok() { self.debug_message = "⌫ Character deleted".to_string(); }
+        Ok(result?)
+    }
+
+    fn delete_forward(&mut self) -> anyhow::Result<()> {
+        let result = self.editor.delete_forward();
+        if result.is_ok() { self.debug_message = "⌦ Character deleted".to_string(); }
+        Ok(result?)
+    }
+
+    // Delegate methods
+    fn current_field(&self) -> usize { self.editor.current_field() }
+    fn cursor_position(&self) -> usize { self.editor.cursor_position() }
+    fn mode(&self) -> AppMode { self.editor.mode() }
+    fn current_text(&self) -> &str { self.editor.current_text() }
+    fn data_provider(&self) -> &D { self.editor.data_provider() }
+    fn ui_state(&self) -> &canvas::EditorState { self.editor.ui_state() }
+    fn set_mode(&mut self, mode: AppMode) { self.editor.set_mode(mode); }
+
+    fn next_field(&mut self) {
+        match self.editor.next_field() {
+            Ok(()) => { self.update_field_validation_status(); self.field_switch_blocked = false; self.block_reason = None; }
+            Err(e) => { self.field_switch_blocked = true; self.block_reason = Some(e.to_string()); self.debug_message = format!("🚫 Cannot move to next field: {}", e); }
+        }
+    }
+
+    fn prev_field(&mut self) {
+        match self.editor.prev_field() {
+            Ok(()) => { self.update_field_validation_status(); self.field_switch_blocked = false; self.block_reason = None; }
+            Err(e) => { self.field_switch_blocked = true; self.block_reason = Some(e.to_string()); self.debug_message = format!("🚫 Cannot move to previous field: {}", e); }
+        }
+    }
+
+    fn set_debug_message(&mut self, msg: String) { self.debug_message = msg; }
+    fn debug_message(&self) -> &str { &self.debug_message }
+
+    fn update_field_validation_status(&mut self) {
+        if !self.validation_enabled { return; }
+        if let Some(result) = self.editor.current_field_validation() {
+            match result {
+                ValidationResult::Valid => { self.debug_message = format!("Field {}: ✅ Pattern valid", self.editor.current_field() + 1); }
+                ValidationResult::Warning { message } => { self.debug_message = format!("Field {}: ⚠️  {}", self.editor.current_field() + 1, message); }
+                ValidationResult::Error { message } => { self.debug_message = format!("Field {}: ❌ {}", self.editor.current_field() + 1, message); }
+            }
+        }
+    }
+
+    fn get_validation_status(&self) -> String {
+        if !self.validation_enabled { return "❌ DISABLED".to_string(); }
+        if self.field_switch_blocked { return "🚫 SWITCH BLOCKED".to_string(); }
+        let summary = self.editor.validation_summary();
+        if summary.has_errors() { format!("❌ {} ERRORS", summary.error_fields) }
+        else if summary.has_warnings() { format!("⚠️  {} WARNINGS", summary.warning_fields) }
+        else if summary.validated_fields > 0 { format!("✅ {} VALID", summary.valid_fields) }
+        else { "🔍 READY".to_string() }
+    }
+}
+
+// Advanced demo form with creative and edge-case-heavy validation patterns
+struct AdvancedPatternData {
+    fields: Vec<(String, String)>,
+}
+
+impl AdvancedPatternData {
+    fn new() -> Self {
+        Self {
+            fields: vec![
+                ("🕐 Time (HH:MM) - 24hr format".to_string(), "".to_string()),
+                ("🎨 Hex Color (#RRGGBB) - Web colors".to_string(), "".to_string()),
+                ("🌐 IPv4 (XXX.XXX.XXX.XXX) - Network address".to_string(), "".to_string()),
+                ("🏷️  Product Code (ABC-123-XYZ) - Mixed format".to_string(), "".to_string()),
+                ("📅 Date Code (2024W15) - Year + Week".to_string(), "".to_string()),
+                ("🔢 Binary (101010) - Only 0s and 1s".to_string(), "".to_string()),
+                ("🎯 Complex ID (A1-B2C-3D4E) - Multi-rule".to_string(), "".to_string()),
+                ("🚀 Custom Pattern - Advanced logic".to_string(), "".to_string()),
+            ],
+        }
+    }
+}
+
+impl DataProvider for AdvancedPatternData {
+    fn field_count(&self) -> usize { self.fields.len() }
+    fn field_name(&self, index: usize) -> &str { &self.fields[index].0 }
+    fn field_value(&self, index: usize) -> &str { &self.fields[index].1 }
+    fn set_field_value(&mut self, index: usize, value: String) { self.fields[index].1 = value; }
+
+    fn validation_config(&self, field_index: usize) -> Option<ValidationConfig> {
+        match field_index {
+            0 => {
+                // 🕐 Time (HH:MM) - Hours 00-23, Minutes 00-59
+                // This showcases: Multiple position ranges, exact character matching, custom validation
+                let time_pattern = PatternFilters::new()
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Multiple(vec![0, 1, 3, 4]), // Hours and minutes positions
+                        CharacterFilter::Numeric,
+                    ))
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Single(2), // Colon separator
+                        CharacterFilter::Exact(':'),
+                    ));
+
+                Some(ValidationConfigBuilder::new()
+                    .with_pattern_filters(time_pattern)
+                    .with_max_length(5) // HH:MM = 5 characters
+                    .build())
+            }
+            1 => {
+                // 🎨 Hex Color (#RRGGBB) - Web color format
+                // This showcases: OneOf filter with hex digits, exact character at start
+                let hex_digits = vec!['0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','a','b','c','d','e','f'];
+                let hex_color_pattern = PatternFilters::new()
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Single(0), // Hash symbol
+                        CharacterFilter::Exact('#'),
+                    ))
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Range(1, 6), // 6 hex digits for RGB
+                        CharacterFilter::OneOf(hex_digits),
+                    ));
+
+                Some(ValidationConfigBuilder::new()
+                    .with_pattern_filters(hex_color_pattern)
+                    .with_max_length(7) // #RRGGBB = 7 characters
+                    .build())
+            }
+            2 => {
+                // 🌐 IPv4 Address (XXX.XXX.XXX.XXX) - Network address
+                // This showcases: Complex pattern with dots at specific positions
+                let ipv4_pattern = PatternFilters::new()
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Multiple(vec![3, 7, 11]), // Dots at specific positions
+                        CharacterFilter::Exact('.'),
+                    ))
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Multiple(vec![0,1,2,4,5,6,8,9,10,12,13,14]), // Number positions
+                        CharacterFilter::Numeric,
+                    ));
+
+                Some(ValidationConfigBuilder::new()
+                    .with_pattern_filters(ipv4_pattern)
+                    .with_max_length(15) // XXX.XXX.XXX.XXX = up to 15 chars
+                    .build())
+            }
+            3 => {
+                // 🏷️ Product Code (ABC-123-XYZ) - Mixed format sections
+                // This showcases: Different rules for different sections
+                let product_code_pattern = PatternFilters::new()
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Range(0, 2), // First 3 positions: letters
+                        CharacterFilter::Alphabetic,
+                    ))
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Multiple(vec![3, 7]), // Dashes
+                        CharacterFilter::Exact('-'),
+                    ))
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Range(4, 6), // Middle 3 positions: numbers
+                        CharacterFilter::Numeric,
+                    ))
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Range(8, 10), // Last 3 positions: letters
+                        CharacterFilter::Alphabetic,
+                    ));
+
+                Some(ValidationConfigBuilder::new()
+                    .with_pattern_filters(product_code_pattern)
+                    .with_max_length(11) // ABC-123-XYZ = 11 characters
+                    .build())
+            }
+            4 => {
+                // 📅 Date Code (2024W15) - Year + Week format
+                // This showcases: From position filtering and mixed patterns
+                let date_code_pattern = PatternFilters::new()
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Range(0, 3), // Year: 4 digits
+                        CharacterFilter::Numeric,
+                    ))
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Single(4), // Week indicator
+                        CharacterFilter::Exact('W'),
+                    ))
+                    .add_filter(PositionFilter::new(
+                        PositionRange::From(5), // Week number: rest are digits
+                        CharacterFilter::Numeric,
+                    ));
+
+                Some(ValidationConfigBuilder::new()
+                    .with_pattern_filters(date_code_pattern)
+                    .with_max_length(7) // 2024W15 = 7 characters
+                    .build())
+            }
+            5 => {
+                // 🔢 Binary (101010) - Only 0s and 1s
+                // This showcases: OneOf filter with limited character set
+                let binary_pattern = PatternFilters::new()
+                    .add_filter(PositionFilter::new(
+                        PositionRange::From(0), // All positions
+                        CharacterFilter::OneOf(vec!['0', '1']),
+                    ));
+
+                Some(ValidationConfigBuilder::new()
+                    .with_pattern_filters(binary_pattern)
+                    .with_max_length(16) // Allow up to 16 binary digits
+                    .build())
+            }
+            6 => {
+                // 🎯 Complex ID (A1-B2C-3D4E) - Multiple overlapping rules
+                // This showcases: Complex overlapping patterns and edge cases
+                let complex_id_pattern = PatternFilters::new()
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Multiple(vec![0, 3, 6, 8]), // Letter positions
+                        CharacterFilter::Alphabetic,
+                    ))
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Multiple(vec![1, 4, 7, 9]), // Number positions
+                        CharacterFilter::Numeric,
+                    ))
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Multiple(vec![2, 5]), // Dashes
+                        CharacterFilter::Exact('-'),
+                    ))
+                    .add_filter(PositionFilter::new(
+                        PositionRange::Single(5), // Special case: override dash with letter C
+                        CharacterFilter::Alphabetic, // This creates an interesting edge case
+                    ));
+
+                Some(ValidationConfigBuilder::new()
+                    .with_pattern_filters(complex_id_pattern)
+                    .with_max_length(10) // A1-B2C-3D4E = 10 characters
+                    .build())
+            }
+            7 => {
+                // 🚀 Custom Pattern - Advanced logic with custom function
+                // This showcases: Custom validation function for complex rules
+                let custom_pattern = PatternFilters::new()
+                    .add_filter(PositionFilter::new(
+                        PositionRange::From(0),
+                        CharacterFilter::Custom(Arc::new(|c| {
+                            // Advanced rule: Alternating vowels and consonants!
+                            // Even positions (0,2,4...): vowels (a,e,i,o,u)
+                            // Odd positions (1,3,5...): consonants
+                            let vowels = ['a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U'];
+                            
+                            // For demo purposes, we'll just accept alphabetic characters
+                            // In real usage, you'd implement the alternating logic based on position
+                            c.is_alphabetic()
+                        })),
+                    ));
+
+                Some(ValidationConfigBuilder::new()
+                    .with_pattern_filters(custom_pattern)
+                    .with_max_length(12) // Allow up to 12 characters
+                    .build())
+            }
+            _ => None,
+        }
+    }
+}
+
+// Key handling (same structure as before)
+fn handle_key_press(
+    key: KeyCode,
+    modifiers: KeyModifiers,
+    editor: &mut AdvancedPatternFormEditor<AdvancedPatternData>,
+) -> anyhow::Result<bool> {
+    let mode = editor.mode();
+
+    // Quit handling
+    if (key == KeyCode::Char('q') && modifiers.contains(KeyModifiers::CONTROL))
+        || (key == KeyCode::Char('c') && modifiers.contains(KeyModifiers::CONTROL))
+        || key == KeyCode::F(10)
+    {
+        return Ok(false);
+    }
+
+    match (mode, key, modifiers) {
+        // Mode transitions
+        (AppMode::ReadOnly, KeyCode::Char('i'), _) => { editor.enter_edit_mode(); editor.clear_command_buffer(); }
+        (AppMode::ReadOnly, KeyCode::Char('a'), _) => { editor.enter_append_mode(); editor.clear_command_buffer(); }
+        (AppMode::ReadOnly, KeyCode::Char('A'), _) => { editor.move_line_end(); editor.enter_edit_mode(); editor.clear_command_buffer(); }
+        (_, KeyCode::Esc, _) => { if mode == AppMode::Edit { editor.exit_edit_mode(); } else { editor.clear_command_buffer(); } }
+
+        // Validation commands
+        (AppMode::ReadOnly, KeyCode::F(1), _) => { editor.toggle_validation(); }
+
+        // Movement in ReadOnly mode
+        (AppMode::ReadOnly, KeyCode::Char('h'), _) | (AppMode::ReadOnly, KeyCode::Left, _) => { editor.move_left(); editor.clear_command_buffer(); }
+        (AppMode::ReadOnly, KeyCode::Char('l'), _) | (AppMode::ReadOnly, KeyCode::Right, _) => { editor.move_right(); editor.clear_command_buffer(); }
+        (AppMode::ReadOnly, KeyCode::Char('j'), _) | (AppMode::ReadOnly, KeyCode::Down, _) => { editor.move_down(); editor.clear_command_buffer(); }
+        (AppMode::ReadOnly, KeyCode::Char('k'), _) | (AppMode::ReadOnly, KeyCode::Up, _) => { editor.move_up(); editor.clear_command_buffer(); }
+
+        // Movement in Edit mode
+        (AppMode::Edit, KeyCode::Left, _) => { editor.move_left(); }
+        (AppMode::Edit, KeyCode::Right, _) => { editor.move_right(); }
+        (AppMode::Edit, KeyCode::Up, _) => { editor.move_up(); }
+        (AppMode::Edit, KeyCode::Down, _) => { editor.move_down(); }
+
+        // Delete operations
+        (AppMode::Edit, KeyCode::Backspace, _) => { editor.delete_backward()?; }
+        (AppMode::Edit, KeyCode::Delete, _) => { editor.delete_forward()?; }
+
+        // Tab navigation
+        (_, KeyCode::Tab, _) => { editor.next_field(); }
+        (_, KeyCode::BackTab, _) => { editor.prev_field(); }
+
+        // Character input
+        (AppMode::Edit, KeyCode::Char(c), m) if !m.contains(KeyModifiers::CONTROL) => {
+            editor.insert_char(c)?;
+        }
+
+        // Debug info
+        (AppMode::ReadOnly, KeyCode::Char('?'), _) => {
+            let summary = editor.editor.validation_summary();
+            editor.set_debug_message(format!(
+                "Field {}/{}, Pos {}, Mode: {:?}, Advanced patterns: {} configured",
+                editor.current_field() + 1,
+                editor.data_provider().field_count(),
+                editor.cursor_position(),
+                editor.mode(),
+                summary.total_fields
+            ));
+        }
+
+        _ => {
+            if editor.has_pending_command() {
+                editor.clear_command_buffer();
+                editor.set_debug_message("Invalid command sequence".to_string());
+            }
+        }
+    }
+
+    Ok(true)
+}
+
+fn run_app<B: Backend>(
+    terminal: &mut Terminal<B>,
+    mut editor: AdvancedPatternFormEditor<AdvancedPatternData>,
+) -> io::Result<()> {
+    loop {
+        terminal.draw(|f| ui(f, &editor))?;
+
+        if let Event::Key(key) = event::read()? {
+            match handle_key_press(key.code, key.modifiers, &mut editor) {
+                Ok(should_continue) => {
+                    if !should_continue {
+                        break;
+                    }
+                }
+                Err(e) => {
+                    editor.set_debug_message(format!("Error: {}", e));
+                }
+            }
+        }
+    }
+
+    Ok(())
+}
+
+fn ui(f: &mut Frame, editor: &AdvancedPatternFormEditor<AdvancedPatternData>) {
+    let chunks = Layout::default()
+        .direction(Direction::Vertical)
+        .constraints([Constraint::Min(8), Constraint::Length(15)])
+        .split(f.area());
+
+    render_canvas_default(f, chunks[0], &editor.editor);
+    render_advanced_validation_status(f, chunks[1], editor);
+}
+
+fn render_advanced_validation_status(
+    f: &mut Frame,
+    area: Rect,
+    editor: &AdvancedPatternFormEditor<AdvancedPatternData>,
+) {
+    let chunks = Layout::default()
+        .direction(Direction::Vertical)
+        .constraints([
+            Constraint::Length(3), // Status bar
+            Constraint::Length(5), // Validation summary
+            Constraint::Length(7), // Help
+        ])
+        .split(area);
+
+    // Status bar
+    let mode_text = match editor.mode() {
+        AppMode::Edit => "INSERT",
+        AppMode::ReadOnly => "NORMAL",
+        _ => "OTHER",
+    };
+
+    let validation_status = editor.get_validation_status();
+    let status_text = format!("-- {} -- {} | Advanced Patterns: {}", mode_text, editor.debug_message(), validation_status);
+
+    let status = Paragraph::new(Line::from(Span::raw(status_text)))
+        .block(Block::default().borders(Borders::ALL).title("🚀 Advanced Pattern Validation"));
+
+    f.render_widget(status, chunks[0]);
+
+    // Enhanced validation summary
+    let summary = editor.editor.validation_summary();
+    let field_info = match editor.current_field() {
+        0 => "Time format (HH:MM) - Tests exact chars + numeric ranges",
+        1 => "Hex color (#RRGGBB) - Tests OneOf filter with case insensitive",
+        2 => "IPv4 address - Tests complex dot positioning",
+        3 => "Product code (ABC-123-XYZ) - Tests section-based patterns",
+        4 => "Date code (2024W15) - Tests From position filtering",
+        5 => "Binary input - Tests limited character set (0,1 only)",
+        6 => "Complex ID - Tests overlapping/conflicting rules",
+        7 => "Custom pattern - Tests advanced custom validation logic",
+        _ => "Unknown field",
+    };
+
+    let summary_text = if editor.validation_enabled {
+        format!(
+            "📊 Advanced Pattern Summary: {} fields with complex rules\n\
+             Current Field: {}\n\
+             ✅ Valid: {}  ⚠️  Warnings: {}  ❌ Errors: {}  📈 Progress: {:.0}%\n\
+             🎯 Pattern Focus: {}",
+            summary.total_fields,
+            editor.current_field() + 1,
+            summary.valid_fields,
+            summary.warning_fields,
+            summary.error_fields,
+            summary.completion_percentage() * 100.0,
+            field_info
+        )
+    } else {
+        "❌ Advanced pattern validation is DISABLED\nPress F1 to enable and see the magic!".to_string()
+    };
+
+    let summary_style = if summary.has_errors() {
+        Style::default().fg(Color::Red)
+    } else if summary.has_warnings() {
+        Style::default().fg(Color::Yellow)
+    } else {
+        Style::default().fg(Color::Green)
+    };
+
+    let validation_summary = Paragraph::new(summary_text)
+        .block(Block::default().borders(Borders::ALL).title("🎯 Advanced Pattern Analysis"))
+        .style(summary_style)
+        .wrap(Wrap { trim: true });
+
+    f.render_widget(validation_summary, chunks[1]);
+
+    // Enhanced help text
+    let help_text = match editor.mode() {
+        AppMode::ReadOnly => {
+            "🚀 ADVANCED PATTERN SHOWCASE - Each field demonstrates different edge cases!\n\
+             🕐 Time: Numeric+exact chars  🎨 Hex: OneOf with case-insensitive  🌐 IPv4: Complex positioning\n\
+             🏷️  Product: Multi-section rules  📅 Date: From-position filtering  🔢 Binary: Limited charset\n\
+             🎯 Complex: Overlapping rules  🚀 Custom: Advanced logic functions\n\
+             \n\
+             Movement: hjkl/arrows=move, Tab/Shift+Tab=fields, i/a=insert, F1=toggle, ?=info"
+        }
+        AppMode::Edit => {
+            "✏️  INSERT MODE - Testing advanced pattern validation!\n\
+             Each character is validated against complex rules in real-time\n\
+             Try entering invalid characters to see detailed error messages\n\
+             arrows=move, Backspace/Del=delete, Esc=normal, Tab=next field"
+        }
+        _ => "🚀 Advanced Pattern Validation Active!"
+    };
+
+    let help = Paragraph::new(help_text)
+        .block(Block::default().borders(Borders::ALL).title("🎯 Advanced Pattern Commands & Info"))
+        .style(Style::default().fg(Color::Gray))
+        .wrap(Wrap { trim: true });
+
+    f.render_widget(help, chunks[2]);
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    println!("🚀 Canvas Advanced Pattern Validation Demo");
+    println!("✅ validation feature: ENABLED");
+    println!("✅ gui feature: ENABLED");
+    println!("🎯 Advanced pattern filtering: ACTIVE");
+    println!("🧪 Edge cases and complex patterns: READY");
+    println!("💡 Each field showcases different validation capabilities!");
+    println!();
+
+    enable_raw_mode()?;
+    let mut stdout = io::stdout();
+    execute!(stdout, EnterAlternateScreen, EnableMouseCapture)?;
+    let backend = CrosstermBackend::new(stdout);
+    let mut terminal = Terminal::new(backend)?;
+
+    let data = AdvancedPatternData::new();
+    let editor = AdvancedPatternFormEditor::new(data);
+
+    let res = run_app(&mut terminal, editor);
+
+    disable_raw_mode()?;
+    execute!(
+        terminal.backend_mut(),
+        LeaveAlternateScreen,
+        DisableMouseCapture
+    )?;
+    terminal.show_cursor()?;
+
+    if let Err(err) = res {
+        println!("{:?}", err);
+    }
+
+    println!("🚀 Advanced pattern validation demo completed!");
+    println!("🎯 Hope you enjoyed seeing all the edge cases in action!");
+    Ok(())
+}

canvas/src/lib.rs

@@ -35,7 +35,7 @@ pub use canvas::actions::{CanvasAction, ActionResult};
 pub use validation::{
     ValidationConfig, ValidationResult, ValidationError,
     CharacterLimits, ValidationConfigBuilder, ValidationState,
-    ValidationSummary,
+    ValidationSummary, PatternFilters, PositionFilter, PositionRange, CharacterFilter,
 };
 
 // Theming and GUI

canvas/src/validation/config.rs

@@ -1,29 +1,24 @@
 // src/validation/config.rs
 //! Validation configuration types and builders
 
-use crate::validation::CharacterLimits;
-use serde::{Deserialize, Serialize};
+use crate::validation::{CharacterLimits, PatternFilters};
 
 /// Main validation configuration for a field
-#[derive(Debug, Clone, Default, Serialize, Deserialize)]
+#[derive(Debug, Clone, Default)]
 pub struct ValidationConfig {
     /// Character limit configuration
     pub character_limits: Option<CharacterLimits>,
     
-    /// Future: Predefined patterns
-    #[serde(skip)]
-    pub patterns: Option<()>, // Placeholder for future implementation
+    /// Pattern filtering configuration
+    pub pattern_filters: Option<PatternFilters>,
     
     /// Future: Reserved characters
-    #[serde(skip)]
     pub reserved_chars: Option<()>, // Placeholder for future implementation
     
     /// Future: Custom formatting
-    #[serde(skip)]
     pub custom_formatting: Option<()>, // Placeholder for future implementation
     
     /// Future: External validation
-    #[serde(skip)]
     pub external_validation: Option<()>, // Placeholder for future implementation
 }
 
@@ -45,6 +40,12 @@ impl ValidationConfigBuilder {
         self
     }
     
+    /// Set pattern filters for the field
+    pub fn with_pattern_filters(mut self, filters: PatternFilters) -> Self {
+        self.config.pattern_filters = Some(filters);
+        self
+    }
+    
     /// Set maximum number of characters (convenience method)
     pub fn with_max_length(mut self, max_length: usize) -> Self {
         self.config.character_limits = Some(CharacterLimits::new(max_length));
@@ -114,6 +115,13 @@ impl ValidationConfig {
             .build()
     }
     
+    /// Create a configuration with pattern filters
+    pub fn with_patterns(patterns: PatternFilters) -> Self {
+        ValidationConfigBuilder::new()
+            .with_pattern_filters(patterns)
+            .build()
+    }
+    
     /// Validate a character insertion at a specific position
     pub fn validate_char_insertion(
         &self,
@@ -130,6 +138,13 @@ impl ValidationConfig {
             }
         }
         
+        // Pattern filters validation
+        if let Some(ref patterns) = self.pattern_filters {
+            if let Err(message) = patterns.validate_char_at_position(position, character) {
+                return ValidationResult::error(message);
+            }
+        }
+        
         // Future: Add other validation types here
         
         ValidationResult::Valid
@@ -146,6 +161,13 @@ impl ValidationConfig {
             }
         }
         
+        // Pattern filters validation
+        if let Some(ref patterns) = self.pattern_filters {
+            if let Err(message) = patterns.validate_text(text) {
+                return ValidationResult::error(message);
+            }
+        }
+        
         // Future: Add other validation types here
         
         ValidationResult::Valid
@@ -153,8 +175,7 @@ impl ValidationConfig {
     
     /// Check if any validation rules are configured
     pub fn has_validation(&self) -> bool {
-        self.character_limits.is_some()
-        // || self.patterns.is_some()
+        self.character_limits.is_some() || self.pattern_filters.is_some()
         // || self.reserved_chars.is_some()
         // || self.custom_formatting.is_some()
         // || self.external_validation.is_some()
@@ -232,4 +253,48 @@ mod tests {
         let result = config.validate_char_insertion("tests", 5, 'x');
         assert!(!result.is_acceptable());
     }
+    
+    #[test]
+    fn test_config_with_patterns() {
+        use crate::validation::{PatternFilters, PositionFilter, PositionRange, CharacterFilter};
+        
+        let patterns = PatternFilters::new()
+            .add_filter(PositionFilter::new(
+                PositionRange::Range(0, 1),
+                CharacterFilter::Alphabetic,
+            ));
+        
+        let config = ValidationConfig::with_patterns(patterns);
+        assert!(config.has_validation());
+        
+        // Test valid pattern insertion
+        let result = config.validate_char_insertion("", 0, 'A');
+        assert!(result.is_acceptable());
+        
+        // Test invalid pattern insertion  
+        let result = config.validate_char_insertion("", 0, '1');
+        assert!(!result.is_acceptable());
+    }
+    
+    #[test]
+    fn test_config_builder_with_patterns() {
+        use crate::validation::{PatternFilters, PositionFilter, PositionRange, CharacterFilter};
+        
+        let patterns = PatternFilters::license_plate();
+        let config = ValidationConfigBuilder::new()
+            .with_pattern_filters(patterns)
+            .with_max_length(5)
+            .build();
+        
+        assert!(config.has_validation());
+        assert!(config.character_limits.is_some());
+        assert!(config.pattern_filters.is_some());
+        
+        // Test pattern validation
+        let result = config.validate_content("AB123");
+        assert!(result.is_acceptable());
+        
+        let result = config.validate_content("A1123");
+        assert!(!result.is_acceptable());
+    }
 }

canvas/src/validation/mod.rs

@@ -1,13 +1,16 @@
+// src/validation/mod.rs
 //! Validation module for canvas form fields
 
 pub mod config;
 pub mod limits;
 pub mod state;
+pub mod patterns;
 
 // Re-export main types
 pub use config::{ValidationConfig, ValidationResult, ValidationConfigBuilder};
 pub use limits::{CharacterLimits, LimitCheckResult};
 pub use state::{ValidationState, ValidationSummary};
+pub use patterns::{PatternFilters, PositionFilter, PositionRange, CharacterFilter};
 
 /// Validation error types
 #[derive(Debug, Clone, thiserror::Error)]
@@ -18,6 +21,9 @@ pub enum ValidationError {
     #[error("Invalid character '{char}' at position {position}")]
     InvalidCharacter { char: char, position: usize },
     
+    #[error("Pattern validation failed: {message}")]
+    PatternValidationFailed { message: String },
+    
     #[error("Validation configuration error: {message}")]
     ConfigurationError { message: String },
 }

canvas/src/validation/patterns.rs

@@ -0,0 +1,326 @@
+// src/validation/patterns.rs
+//! Position-based pattern filtering for validation
+
+use serde::{Deserialize, Serialize};
+use std::sync::Arc;
+
+/// A filter that applies to specific character positions in a field
+#[derive(Debug, Clone)]
+pub struct PositionFilter {
+    /// Which positions this filter applies to
+    pub positions: PositionRange,
+    /// What type of character filter to apply
+    pub filter: CharacterFilter,
+}
+
+/// Defines which character positions a filter applies to
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub enum PositionRange {
+    /// Single position (e.g., position 3 only)
+    Single(usize),
+    /// Range of positions (e.g., positions 0-2, inclusive)
+    Range(usize, usize),
+    /// From position onwards (e.g., position 4 and beyond)
+    From(usize),
+    /// Multiple specific positions (e.g., positions 0, 2, 5)
+    Multiple(Vec<usize>),
+}
+
+/// Types of character filters that can be applied
+pub enum CharacterFilter {
+    /// Allow only alphabetic characters (a-z, A-Z)
+    Alphabetic,
+    /// Allow only numeric characters (0-9)
+    Numeric,
+    /// Allow alphanumeric characters (a-z, A-Z, 0-9)
+    Alphanumeric,
+    /// Allow only exact character match
+    Exact(char),
+    /// Allow any character from the provided set
+    OneOf(Vec<char>),
+    /// Custom user-defined filter function
+    Custom(Arc<dyn Fn(char) -> bool + Send + Sync>),
+}
+
+// Manual implementations for Debug and Clone
+impl std::fmt::Debug for CharacterFilter {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            CharacterFilter::Alphabetic => write!(f, "Alphabetic"),
+            CharacterFilter::Numeric => write!(f, "Numeric"),
+            CharacterFilter::Alphanumeric => write!(f, "Alphanumeric"),
+            CharacterFilter::Exact(ch) => write!(f, "Exact('{}')", ch),
+            CharacterFilter::OneOf(chars) => write!(f, "OneOf({:?})", chars),
+            CharacterFilter::Custom(_) => write!(f, "Custom(<function>)"),
+        }
+    }
+}
+
+impl Clone for CharacterFilter {
+    fn clone(&self) -> Self {
+        match self {
+            CharacterFilter::Alphabetic => CharacterFilter::Alphabetic,
+            CharacterFilter::Numeric => CharacterFilter::Numeric,
+            CharacterFilter::Alphanumeric => CharacterFilter::Alphanumeric,
+            CharacterFilter::Exact(ch) => CharacterFilter::Exact(*ch),
+            CharacterFilter::OneOf(chars) => CharacterFilter::OneOf(chars.clone()),
+            CharacterFilter::Custom(func) => CharacterFilter::Custom(Arc::clone(func)),
+        }
+    }
+}
+
+impl PositionRange {
+    /// Check if a position is included in this range
+    pub fn contains(&self, position: usize) -> bool {
+        match self {
+            PositionRange::Single(pos) => position == *pos,
+            PositionRange::Range(start, end) => position >= *start && position <= *end,
+            PositionRange::From(start) => position >= *start,
+            PositionRange::Multiple(positions) => positions.contains(&position),
+        }
+    }
+
+    /// Get all positions up to a given length that this range covers
+    pub fn positions_up_to(&self, max_length: usize) -> Vec<usize> {
+        match self {
+            PositionRange::Single(pos) => {
+                if *pos < max_length { vec![*pos] } else { vec![] }
+            },
+            PositionRange::Range(start, end) => {
+                let actual_end = (*end).min(max_length.saturating_sub(1));
+                if *start <= actual_end {
+                    (*start..=actual_end).collect()
+                } else {
+                    vec![]
+                }
+            },
+            PositionRange::From(start) => {
+                if *start < max_length {
+                    (*start..max_length).collect()
+                } else {
+                    vec![]
+                }
+            },
+            PositionRange::Multiple(positions) => {
+                positions.iter()
+                    .filter(|&&pos| pos < max_length)
+                    .copied()
+                    .collect()
+            },
+        }
+    }
+}
+
+impl CharacterFilter {
+    /// Test if a character passes this filter
+    pub fn accepts(&self, ch: char) -> bool {
+        match self {
+            CharacterFilter::Alphabetic => ch.is_alphabetic(),
+            CharacterFilter::Numeric => ch.is_numeric(),
+            CharacterFilter::Alphanumeric => ch.is_alphanumeric(),
+            CharacterFilter::Exact(expected) => ch == *expected,
+            CharacterFilter::OneOf(chars) => chars.contains(&ch),
+            CharacterFilter::Custom(func) => func(ch),
+        }
+    }
+
+    /// Get a human-readable description of this filter
+    pub fn description(&self) -> String {
+        match self {
+            CharacterFilter::Alphabetic => "alphabetic characters (a-z, A-Z)".to_string(),
+            CharacterFilter::Numeric => "numeric characters (0-9)".to_string(),
+            CharacterFilter::Alphanumeric => "alphanumeric characters (a-z, A-Z, 0-9)".to_string(),
+            CharacterFilter::Exact(ch) => format!("exactly '{}'", ch),
+            CharacterFilter::OneOf(chars) => {
+                let char_list: String = chars.iter().collect();
+                format!("one of: {}", char_list)
+            },
+            CharacterFilter::Custom(_) => "custom filter".to_string(),
+        }
+    }
+}
+
+impl PositionFilter {
+    /// Create a new position filter
+    pub fn new(positions: PositionRange, filter: CharacterFilter) -> Self {
+        Self { positions, filter }
+    }
+
+    /// Validate a character at a specific position
+    pub fn validate_position(&self, position: usize, character: char) -> bool {
+        if self.positions.contains(position) {
+            self.filter.accepts(character)
+        } else {
+            true // Position not covered by this filter, allow any character
+        }
+    }
+
+    /// Get error message for invalid character at position
+    pub fn error_message(&self, position: usize, character: char) -> Option<String> {
+        if self.positions.contains(position) && !self.filter.accepts(character) {
+            Some(format!(
+                "Position {} requires {} but got '{}'",
+                position,
+                self.filter.description(),
+                character
+            ))
+        } else {
+            None
+        }
+    }
+}
+
+/// A collection of position filters for a field
+#[derive(Debug, Clone, Default)]
+pub struct PatternFilters {
+    filters: Vec<PositionFilter>,
+}
+
+impl PatternFilters {
+    /// Create empty pattern filters
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Add a position filter
+    pub fn add_filter(mut self, filter: PositionFilter) -> Self {
+        self.filters.push(filter);
+        self
+    }
+
+    /// Add multiple filters
+    pub fn add_filters(mut self, filters: Vec<PositionFilter>) -> Self {
+        self.filters.extend(filters);
+        self
+    }
+
+    /// Validate a character at a specific position against all applicable filters
+    pub fn validate_char_at_position(&self, position: usize, character: char) -> Result<(), String> {
+        for filter in &self.filters {
+            if let Some(error) = filter.error_message(position, character) {
+                return Err(error);
+            }
+        }
+        Ok(())
+    }
+
+    /// Validate entire text against all filters
+    pub fn validate_text(&self, text: &str) -> Result<(), String> {
+        for (position, character) in text.char_indices() {
+            if let Err(error) = self.validate_char_at_position(position, character) {
+                return Err(error);
+            }
+        }
+        Ok(())
+    }
+
+    /// Check if any filters are configured
+    pub fn has_filters(&self) -> bool {
+        !self.filters.is_empty()
+    }
+
+    /// Get all configured filters
+    pub fn filters(&self) -> &[PositionFilter] {
+        &self.filters
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_position_range_contains() {
+        assert!(PositionRange::Single(3).contains(3));
+        assert!(!PositionRange::Single(3).contains(2));
+
+        assert!(PositionRange::Range(1, 4).contains(3));
+        assert!(!PositionRange::Range(1, 4).contains(5));
+
+        assert!(PositionRange::From(2).contains(5));
+        assert!(!PositionRange::From(2).contains(1));
+
+        assert!(PositionRange::Multiple(vec![0, 2, 5]).contains(2));
+        assert!(!PositionRange::Multiple(vec![0, 2, 5]).contains(3));
+    }
+
+    #[test]
+    fn test_position_range_positions_up_to() {
+        assert_eq!(PositionRange::Single(3).positions_up_to(5), vec![3]);
+        assert_eq!(PositionRange::Single(5).positions_up_to(3), vec![]);
+
+        assert_eq!(PositionRange::Range(1, 3).positions_up_to(5), vec![1, 2, 3]);
+        assert_eq!(PositionRange::Range(1, 5).positions_up_to(3), vec![1, 2]);
+
+        assert_eq!(PositionRange::From(2).positions_up_to(5), vec![2, 3, 4]);
+
+        assert_eq!(PositionRange::Multiple(vec![0, 2, 5]).positions_up_to(4), vec![0, 2]);
+    }
+
+    #[test]
+    fn test_character_filter_accepts() {
+        assert!(CharacterFilter::Alphabetic.accepts('a'));
+        assert!(CharacterFilter::Alphabetic.accepts('Z'));
+        assert!(!CharacterFilter::Alphabetic.accepts('1'));
+
+        assert!(CharacterFilter::Numeric.accepts('5'));
+        assert!(!CharacterFilter::Numeric.accepts('a'));
+
+        assert!(CharacterFilter::Alphanumeric.accepts('a'));
+        assert!(CharacterFilter::Alphanumeric.accepts('5'));
+        assert!(!CharacterFilter::Alphanumeric.accepts('-'));
+
+        assert!(CharacterFilter::Exact('x').accepts('x'));
+        assert!(!CharacterFilter::Exact('x').accepts('y'));
+
+        assert!(CharacterFilter::OneOf(vec!['a', 'b', 'c']).accepts('b'));
+        assert!(!CharacterFilter::OneOf(vec!['a', 'b', 'c']).accepts('d'));
+    }
+
+    #[test]
+    fn test_position_filter_validation() {
+        let filter = PositionFilter::new(
+            PositionRange::Range(0, 1),
+            CharacterFilter::Alphabetic,
+        );
+
+        assert!(filter.validate_position(0, 'A'));
+        assert!(filter.validate_position(1, 'b'));
+        assert!(!filter.validate_position(0, '1'));
+        assert!(filter.validate_position(2, '1')); // Position 2 not covered, allow anything
+    }
+
+    #[test]
+    fn test_pattern_filters_validation() {
+        let patterns = PatternFilters::new()
+            .add_filter(PositionFilter::new(
+                PositionRange::Range(0, 1),
+                CharacterFilter::Alphabetic,
+            ))
+            .add_filter(PositionFilter::new(
+                PositionRange::Range(2, 4),
+                CharacterFilter::Numeric,
+            ));
+
+        // Valid pattern: AB123
+        assert!(patterns.validate_text("AB123").is_ok());
+
+        // Invalid: number in alphabetic position
+        assert!(patterns.validate_text("A1123").is_err());
+
+        // Invalid: letter in numeric position
+        assert!(patterns.validate_text("AB1A3").is_err());
+    }
+
+    #[test]
+    fn test_custom_filter() {
+        let pattern = PatternFilters::new()
+            .add_filter(PositionFilter::new(
+                PositionRange::From(0),
+                CharacterFilter::Custom(Arc::new(|c| c.is_lowercase())),
+            ));
+
+        assert!(pattern.validate_text("hello").is_ok());
+        assert!(pattern.validate_text("Hello").is_err()); // Uppercase not allowed
+    }
+}